Electron tube

Abstract

This electron tube is provided with: a photoelectric conversion unit that emits photoelectrons corresponding to incident light; an electron detection unit that receives the photoelectrons from the photoelectric conversion unit; a gate electrode section disposed between the photoelectric conversion section and the electron detection section; and a case unit that accommodates the photoelectric conversion unit, the electron detection unit, and the gate electrode unit. The case part has a cover part that fixes the photoelectric conversion part and constitutes one end side of the case part. The gate electrode section includes: a main body section that controls the passage of photoelectrons by applying a voltage; and a power supply unit that supports the main body so as to be separated from the photoelectric conversion unit, and applies a voltage to the main body. The power supply part is held by the cover part.

Description

Technical Field

[0001] The present disclosure relates to an electron tube. Background Art

[0002] An electron tube is known that includes a photoelectric conversion unit that emits photoelectrons in response to incident light, an electron detection unit that receives photoelectrons from the photoelectric conversion unit, and a housing that houses the photoelectric conversion unit and the electron detection unit (for example, see Patent Document 1). [Prior art literature] [Patent Document]

[0003] Patent Document 1: U.S. Patent No. 5,374,826 Summary of the Invention [Problems to be solved by the invention]

[0004] In some of these electron tubes, a gate electrode portion is disposed between a photoelectric converter and an electron detector within a housing to control the passage of photoelectrons by applying a voltage. However, in such electron tubes, the influence of the electrostatic capacitance between the photoelectric converter and the gate electrode makes it difficult to quickly switch the voltage applied to the gate electrode portion, making it difficult to achieve high-speed operation of the gate electrode portion.

[0005] An object of the present disclosure is to provide an electron tube capable of increasing the speed of operation of a gate electrode portion. [Technical means to solve the problem]

[0006] (1) An electron tube according to one embodiment of the present disclosure includes: a photoelectric conversion portion that emits photoelectrons corresponding to incident light; an electron detection portion that receives photoelectrons from the photoelectric conversion portion; a gate electrode portion that is arranged between the photoelectric conversion portion and the electron detection portion; and a housing portion that accommodates the photoelectric conversion portion, the electron detection portion, and the gate electrode portion; the housing portion has a cover portion that fixes the photoelectric conversion portion and constitutes one end side of the housing portion; the gate electrode portion includes a main body portion that controls the passage of photoelectrons by applying a voltage; and a power supply portion that supports the main body portion in a manner separated from the photoelectric conversion portion and applies a voltage to the main body portion; and the power supply portion is held by the cover portion.

[0007] In this electron tube, the gate electrode's power supply is held by the cover, eliminating the need to position and hold the power supply parallel to the photoelectric converter. This reduces the capacitance between the photoelectric converter and the gate electrode. Consequently, switching of the voltage applied to the gate electrode is accelerated, enabling faster gate electrode operation.

[0008] (2) The electron tube according to (1) above may include a focusing electrode portion disposed between the photoelectric conversion portion and the electron detection portion so as to face the photoelectric conversion portion and focus photoelectrons from the photoelectric conversion portion; and a gate electrode portion electrically connected to the focusing electrode portion. In this case, gate operation and focusing of photoelectrons can be reliably controlled.

[0009] (3) In the electron tube according to (2) above, the gate electrode portion and the focusing electrode portion may be provided as a single unit. In this case, the gate electrode portion and the focusing electrode portion can be efficiently arranged.

[0010] (4) In the electron tube according to any one of (1) to (3) above, the power supply unit may include: a plurality of rod-shaped members fixed to the cover, one end of each member being located within the housing; and a connecting portion connecting one end of each of the plurality of rod-shaped members to the main body. In this case, since the main body of the gate electrode unit is supported within the housing by being suspended from the cover via the plurality of rod-shaped members, the electrostatic capacitance between the photoelectric conversion unit and the gate electrode can be efficiently reduced.

[0011] (5) In the electron tube according to (4), the plurality of rods may include: a first rod extending through the cover; and a second rod having the other end embedded in the cover. In this case, since the second rod can be shortened compared to the first rod by embedding the other end in the cover, the electrostatic capacitance between the photoelectric conversion unit and the gate electrode can be further efficiently reduced.

[0012] (6) The electron tube according to any one of (1) to (5) above may include a first electric field concentration mitigation electrode portion electrically connected to the cover portion so as to be at the same potential as the photoelectric conversion portion, mitigating the concentration of the electric field formed inside the housing portion; and a portion of the first electric field concentration mitigation electrode portion is located closer to the electron detection portion than the main body portion in the relative direction of the photoelectric conversion portion and the electron detection portion. In this case, the first electric field concentration mitigation electrode portion mitigates the concentration of the electric field inside the housing portion, thereby improving the withstand voltage of the electron tube.

[0013] (7) The electron tube according to (4) or (5) above may include a second electric field concentration mitigation electrode portion electrically connected to the cover portion so as to be at the same potential as the photoelectric conversion portion, mitigating the concentration of the electric field formed inside the housing portion; and an end portion of the second electric field concentration mitigation electrode portion on the inner side of the housing portion is located closer to the electron detection portion than the main body portion in the relative direction between the photoelectric conversion portion and the electron detection portion, and extends to a position close to the power supply portion in a direction intersecting the relative direction. In this case, the second electric field concentration mitigation electrode portion mitigates the concentration of the electric field inside the housing portion, thereby improving the withstand voltage of the electron tube.

[0014] (8) In the electron tube according to (7) above, it is possible that the rod-shaped body is fixed to the cover via the airtight seal portion, and the end portion of the second electric field concentration mitigation electrode portion, which is located inside the housing, extends in the intersecting direction until it reaches the airtight seal portion. In this case, the second electric field concentration mitigation electrode portion further mitigates the concentration of the electric field inside the housing portion, thereby further improving the withstand voltage of the electron tube.

[0015] (9) The electron tube according to (4) or (5) above may further include a third electric field concentration mitigation electrode portion, the third electric field concentration mitigation electrode portion being electrically connected to the lid portion so as to be at the same potential as the photoelectric conversion portion, mitigating the concentration of the electric field formed inside the housing portion; and the end portion of the third electric field concentration mitigation electrode portion on the inner side of the housing portion is located closer to the electron detection portion than the connection portion between the rod-shaped body and the connection portion in the relative direction of the photoelectric conversion portion and the electron detection portion. In this case, the third electric field concentration mitigation electrode portion mitigates the concentration of the electric field inside the housing portion, thereby improving the withstand voltage of the electron tube.

[0016] (10) In the electron tube according to (9), one end portion of the third electric field concentration mitigation electrode portion may extend in a direction intersecting the relative direction until it reaches the connection portion. In this case, the third electric field concentration mitigation electrode portion further mitigates the concentration of the electric field inside the housing portion, thereby further improving the withstand voltage of the electron tube.

[0017] (11) The electron tube according to (4) or (5) above may include a fourth electric field concentration mitigation electrode portion, the fourth electric field concentration mitigation electrode portion extending in a cross direction intersecting the relative direction of the photoelectric conversion portion and the electron detection portion, with one end portion located inside the housing portion and the other end portion located outside the housing portion, thereby mitigating the concentration of the electric field formed inside the housing portion; one end portion of the fourth electric field concentration mitigation electrode portion is located closer to the electron detection portion than the connection point between the rod-shaped body and the connection portion in the relative direction, and extends in the cross direction to a position close to the power supply portion. In this case, the fourth electric field concentration mitigation electrode portion mitigates the concentration of the electric field inside the housing portion, thereby improving the withstand voltage of the electron tube.

[0018] (12) In the electron tube according to (11), one end portion of the fourth electric field concentration mitigation electrode portion may extend in the intersecting direction until it reaches the connection portion. In this case, the fourth electric field concentration mitigation electrode portion further mitigates the concentration of the electric field inside the housing portion, thereby further improving the withstand voltage of the electron tube. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide an electron tube capable of increasing the speed of operation of a gate electrode portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a cross-sectional view of the electron tube according to the first embodiment. Figure 2 To display Figure 1 A three-dimensional view of the gate electrode portion. Figure 3 To display Figure 1 Another stereoscopic view of the gate electrode portion. Figure 4 For the general Figure 1 A cross-sectional view showing an enlarged portion of the interior of a electron tube. Figure 5 This is a cross-sectional view showing an enlarged portion of the interior of the electron tube according to the second embodiment. Figure 6 This is a cross-sectional view showing an enlarged portion of the interior of the electron tube according to the third embodiment. Figure 7 This is a cross-sectional view showing an enlarged portion of the interior of an electron tube according to a modified example. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. Figure 1 In the following description, the same or equivalent elements are denoted by the same reference numerals, and repeated descriptions are omitted. The dimensions in the following description do not necessarily correspond to those in the drawings.

[0022] [First embodiment] like Figure 1 As shown, the electron tube 1 is a so-called electron injection multiplication type photosensor (HPD: Hybrid PhotoDetector). The electron tube 1 is used, for example, in an electron microscope. The electron tube 1 includes a housing 2, a photoelectric element 3, and an electron detection unit 4.

[0023] The interior of the housing 2 forms an internal space maintained in a vacuum. The housing 2 is generally cylindrical. As an example, the housing 2 has an outer diameter of approximately 30 mm and a height of approximately 25 mm. The housing 2 accommodates at least the photoelectric element 3 and the electron detection unit 4 therein. The housing 2 includes a tubular side portion 21 having an axis G as its central axis, a cover portion 22 forming one end side (one end portion) of the housing 2, and a base 23 forming the other end side (the other end portion) of the housing 2.

[0024] One end of the side portion 21 is airtightly connected to the cover portion 22 and sealed. The other end of the side portion 21 is airtightly connected to the tube seat 23 and sealed. The cover portion 22 is a disc-shaped member formed by a conductive member having light-shielding properties (for example, a metal material such as Kovar alloy). The cover portion 22 has a cover upper surface 22a and a cover lower surface 22b. The cover upper surface 22a is exposed to the outside of the shell portion 2. The cover lower surface 22b is the surface on the opposite side of the cover upper surface 22a and is exposed to the inside of the shell portion 2. The axis of the cover portion 22 overlaps with the axis G of the shell portion 2. The cover lower surface 22b of the cover portion 22 faces the tube seat 23.

[0025] The stem 23 includes a base 17, a power supply pin 18, a signal pin 19, a barrel 46, and a window 28. The disc-shaped base 17 includes a base main surface 17a and a base back surface 17b. The base main surface 17a is exposed to the inner side of the shell 2. The base back surface 17b is the surface on the opposite side of the base main surface 17a and is exposed to the outer side of the shell 2. The electronic detection unit 4 is mounted on the central part of the base main surface 17a via the substrate 24. As a material for the base 17, for example, copper, which is a metal material with high heat dissipation properties, can be cited, but other metal materials such as kovar, conductive materials, or insulating materials such as ceramics can also be used. The base 17 effectively dissipates the heat generated during the operation of the electronic detection unit 4.

[0026] Power supply pin 18 applies voltage to substrate 24, on which electronic detection unit 4 is mounted. Power supply pin 18 is a rod-shaped conductive member extending parallel to axis G. One end of power supply pin 18 is exposed inside housing 2. The other end of power supply pin 18 is exposed outside housing 2. One end of power supply pin 18 is electrically connected to substrate 24 via a wire (not shown). Power supply pin 18 is insulated from socket 23.

[0027] Signal pin 19 receives a signal from electronic detection unit 4. Signal pin 19 is a rod-shaped conductive member extending parallel to axis G. One end of signal pin 19 is electrically connected to electronic detection unit 4 via substrate 24. The other end of signal pin 19 is exposed outside housing 2. Signal pin 19 is insulated from socket 23.

[0028] The barrel 46 is a cylindrical member that constitutes the light incident hole 26 for receiving light into the interior of the housing 2. The barrel 46 protrudes from the base 17 to the outside of the housing 2 in a direction inclined relative to the axis G. The window 28 is airtightly joined to the flange 47 on the front end side of the barrel 46 via an aluminum ring 48. The window 28 allows light from the outside to pass into the housing 2. The window 28 is formed by a glass material that is transparent to light (for example, quartz or sapphire glass). In the window 28 formed by quartz, light with a shorter wavelength, such as in the ultraviolet region, can be effectively transmitted. Furthermore, the material of the window 28 can also be selected according to the wavelength of the light to be detected.

[0029] The photoelectric element 3 emits photoelectrons corresponding to the incident light. The photoelectric element 3 is a film-shaped portion arranged on the cover 22. The photoelectric element 3 is formed on a concave curved surface 22c that is recessed on the lower surface 22b of the cover 22. The curved surface 22c is a curved surface formed in the cover 22 on the side of the internal space of the shell 2. The curved surface 22c is a parabola of rotation with the axis G as the axis of rotation. The photoelectric element 3 is, for example, an alkaline photoelectric element formed of Sb-K-Cs or the like. As the photoelectric element material, a crystalline photoelectric element material such as GaAsP can also be used. The potential is supplied to the photoelectric element 3 through the cover 22. In this embodiment, since the cover 22 is formed of a conductive member with light-shielding properties as described above, the photoelectric element 3 functions as a reflective photoelectric element and suppresses noise light from entering the photoelectric element 3 from the cover 22 side.

[0030] The electron detection unit 4 is an electron detection unit that receives photoelectrons from the photoelectric surface 3. An example of the electron detection unit 4 is a semiconductor component, and a component with an electron multiplication function is particularly preferred. As such a semiconductor component, an avalanche photodiode can be cited, for example. An avalanche photodiode is a semiconductor component that connects a high-concentration P region and an N region to form a higher electric field sufficient for avalanche amplification. The electron detection unit 4 is arranged on the base main surface 17a of the stem 23 via the substrate 24. The electron detection unit 4 is arranged on the axis G. When the photoelectron is incident on the incident surface of the electron detection unit 4, the photoelectron is multiplied and an electrical signal is output. Therefore, the electron detection unit 4 can also be called an electron multiplication unit.

[0031] In this embodiment, the side portion 21 of the housing 2 includes a first focusing electrode portion 5, an insulating tube portion 12, an intermediate electrode portion 6, an insulating tube portion 14, and an electric field concentration and relaxation electrode portion 7. The first focusing electrode portion 5, the insulating tube portion 12, the intermediate electrode portion 6, the insulating tube portion 14, and the electric field concentration and relaxation electrode portion 7 are arranged in an overlapping manner from the side of the tube base 23 to the side of the cover portion 22. The first focusing electrode portion 5 is an electrode portion arranged between the photoelectric element 3 and the electron detection portion 4. The first focusing electrode portion 5 is the electrode portion closest to the electron detection portion 4. The first focusing electrode portion 5 is arranged directly opposite the electron detection portion 4. The first focusing electrode portion 5 focuses photoelectrons on the electron detection portion 4. The first focusing electrode portion 5 is a conductive member having a roughly cap-shaped structure. The first focusing electrode portion 5 includes a flat plate portion 5x having a circular flat plate shape with its thickness direction being along the axis G, and a peripheral wall portion 5g provided upright on the outer peripheral edge of the flat plate portion 5x. The first focusing electrode 5 is located between the insulating tube 12 and the stem 23, and is airtightly connected to the insulating tube 12 and the stem 23. The first focusing electrode 5 and the stem 23 are set to the same potential. For example, a voltage of 6 kV is applied to the first focusing electrode 5 from an electrically connected power source (not shown).

[0032] The flat plate portion 5x of the first focusing electrode 5 is formed with a light passage hole 5a and a passage hole 5b. The light passage hole 5a is a through hole that guides light passing through the window portion 28 and the light incident hole 26 toward the photoelectric element 3. The passage hole 5b is a through hole that passes at least photoelectrons from the photoelectric element 3. The passage hole 5b is provided in the center portion of the flat plate portion 5x of the first focusing electrode 5. The passage hole 5b is formed in the flat plate portion 5x adjacent to and spaced apart from the light passage hole 5a.

[0033] The insulating cylinders 12 and 14 are insulating members having a cylindrical shape centered on the axis G. They are made of, for example, a ceramic material. The insulating cylinder 12 is positioned between the first focusing electrode 5 and the intermediate electrode 6, providing an airtight connection to both electrodes. The insulating cylinder 14 is positioned between the intermediate electrode 6 and the electric field concentration and relaxation electrode 7, providing an airtight connection to both electrodes.

[0034] The intermediate electrode portion 6 is an electrode portion disposed between the photoelectric element 3 and the first focusing electrode portion 5. The intermediate electrode portion 6 is a flat conductive member having an annular shape centered on the axis G and a thickness along the axis G. The intermediate electrode portion 6 has the function of stabilizing the electric field formed within the housing portion 2. The intermediate electrode portion 6 is airtightly connected to the insulating cylinders 12 and 14 between the intermediate electrode portions 12 and 14. A voltage of 3 kV is applied to the intermediate electrode portion 6 from an electrically connected power source (not shown), for example. The intermediate electrode portion 6 has a through hole 6a provided in the center. The through hole 6a is a through hole that allows at least light to the photoelectric element 3 and photoelectrons from the photoelectric element 3 to pass through. The inner diameter of the through hole 6a is larger than the inner diameter of the through hole 5b.

[0035] The electric field concentration mitigation electrode portion 7 is electrically connected to the lid portion 22 so as to be at the same potential as the photoelectric element 3. In this embodiment, the electric field concentration mitigation electrode portion 7 is an electrode portion that is in direct contact with the lid portion 22. The electric field concentration mitigation electrode portion 7 mitigates the concentration of the electric field formed within the housing portion 2. The electric field concentration mitigation electrode portion 7 has a through hole 7a provided in its center. The inner diameter of the through hole 7a is larger than that of the through hole 6a. Details of the electric field concentration mitigation electrode portion 7 will be described later.

[0036] like Figure 1 、 Figure 2 and Figure 3 As shown, the electron tube 1 of this embodiment includes a second focusing electrode portion 8. The second focusing electrode portion 8 is housed within the housing portion 2. The second focusing electrode portion 8 is an electrode portion disposed between the photoelectric element 3 and the intermediate electrode portion 6. The second focusing electrode portion 8 is a conductive member having a substantially annular plate shape centered about the axis G. The second focusing electrode portion 8 is disposed opposite the photoelectric element 3 and focuses photoelectrons from the photoelectric element 3.

[0037] The second focusing electrode portion 8 includes an annular plate portion 8x having an annular shape with the axis G as its center axis and a flat plate-like shape with its thickness oriented in the direction of the axis G, and a tapered portion 8y continuous with the inner circumference of the annular plate portion 8x. The annular plate portion 8x has a generally polygonal shape (in this embodiment, a generally triangular shape) when viewed along the axis G. The polygonal corners of the annular plate portion 8x are rounded R-shaped. This suppresses disturbances in the electric field caused by these corners, thereby inhibiting discharge. The tapered portion 8y is inclined so as to bend toward the curved surface 22c of the cover portion 22 (the photoelectric element 3 side) and protrudes from the inner circumference of the annular plate portion 8x in a direction that decreases in diameter toward the axis G. The tapered portion 8y has an outer surface shaped like a truncated cone with the axis G as its center axis, with the diameter decreasing toward the curved surface 22c of the cover portion 22 (the photoelectric element 3 side). The second focusing electrode portion 8 has a through hole 8a provided in its center. The passage hole 8a is a through hole that passes at least light toward the photoelectric element 3 and photoelectrons from the photoelectric element 3. The inner diameter of the passage hole 8a is formed to decrease toward the curved surface 22c of the cover 22 (photoelectric element 3).

[0038] At multiple locations along the edge of the annular plate portion 8x of the second focusing electrode unit 8, more specifically at locations corresponding to corners of the roughly polygonal (roughly triangular) shape, rod-shaped bodies 80 formed of a conductive material and extending along the axis G are fixed and connected by, for example, laser welding. The multiple rod-shaped bodies 80 are positioned with one end portion inside the housing 2, while the other end portion is airtightly fixed to the cover 22. Thus, the second focusing electrode unit 8 is suspended and held by the multiple rod-shaped bodies 80 from the cover 22 at a position between the photocathode 3 and the intermediate electrode unit 6 within the housing 2. Furthermore, a voltage is applied to the second focusing electrode unit 8 via the rod-shaped bodies 80 from a power supply (not shown).

[0039] As described above, the first focusing electrode 5 , the intermediate electrode 6 , and the second focusing electrode 8 generate an electric field forming a group of equipotential lines (equipotential surfaces) constituting an electron lens for focusing photoelectrons from the photocathode 3 toward the electron detection unit 4 inside the housing 2 .

[0040] The electron tube 1 of this embodiment includes a gate electrode portion 9. At least a portion of the gate electrode portion 9 is housed within the housing portion 2. The gate electrode portion 9 includes a main body portion 91 that controls the passage of photoelectrons by applying a voltage, and a power supply portion 92 that supports the main body portion 91 at a distance from the photocathode 3 and applies a voltage to the main body portion 91. The gate electrode portion 9 is electrically connected to the second focusing electrode portion 8. In this embodiment, the gate electrode portion 9 and the second focusing electrode portion 8 are integrally provided. In other words, a portion of the gate electrode portion 9 is formed by the second focusing electrode portion 8.

[0041] The main body 91 is the electrode portion closest to the photoelectric element 3. The main body 91 is a conductive member that extends in a curved shape along (imitating) the photoelectric element 3, which is disposed on the curved surface 22c, a parabola of revolution with axis G as its axis of rotation. Specifically, the main body 91 is formed from the parabola of revolution with axis G as its axis of rotation and has a dome-like shape that protrudes toward the photoelectric element 3. The main body 91 is positioned a certain distance from the photoelectric element 3. The main body 91 is separated from the photoelectric element 3 by a substantially constant distance. This allows for uniform grid operation across the entire surface of the photoelectric element 3. The main body 91 is formed from a thin wire-shaped metal member, whose diameter (width) is, for example, smaller than that of the rod-shaped body 80. When viewed from the direction of axis G, the main body 91 forms a network structure, such as a spider's nest, with a circular opening at the center. Specifically, the main body 91 includes, for example, a plurality of concentric ring members of varying diameters, and a plurality of radial members that intersect the ring members and extend radially. Furthermore, the main body 91 is arranged to smoothly continue with the outer surface of the tapered portion 8y of the second focusing electrode 8 in a cross section viewed along the axis G. This suppresses disturbance of the electric field during gate operation and suppresses discharge.

[0042] The power supply unit 92 is composed of the aforementioned multiple rod-shaped members 80 and the second focusing electrode unit 8, and is retained by the cover 22. The multiple rod-shaped members 80 are conductive rod-shaped members with a circular cross-section. The multiple rod-shaped members 80 include a first rod-shaped member 81 that extends through the cover 22 and extends to the outside, and two second rod-shaped members 82 whose other ends are embedded in the cover 22.

[0043] The first rod-shaped body 81 is longer than the second rod-shaped body 82. The first rod-shaped body 81 passes through the cover 22. The other end of the first rod-shaped body 81 is located outside the housing 2. The center portion of the first rod-shaped body 81 is airtightly fixed to the cover 22 by, for example, an airtight seal (hermetic seal) 22h made of an insulating material such as glass. The airtight seal 22h is provided in a through-hole formed in the cover 22. The second rod-shaped body 82 is shorter than the first rod-shaped body. The second rod-shaped body 82 does not pass through the cover 22. The other end of the second rod-shaped body 82 is airtightly fixed to the cover 22 by, for example, an airtight seal (hermetic seal) 22s made of an insulating material such as glass. The airtight seal 22s is provided in a recess of the cover 22 that opens toward the cover lower surface 22b. The airtight seal 22s is not exposed to the outside.

[0044] The second focusing electrode unit 8 forms a connection portion connecting one end portion of the plurality of rod-shaped bodies 80 to the main body 91. The edge of the main body 91 is fixed to the top portion (the edge of the hole 8a) of the tapered portion 8y of the second focusing electrode unit 8 on the cover 22 side. This allows a voltage to be applied to the main body 91 from a power source (not shown) via the first rod-shaped bodies 81.

[0045] As described above, the electron tube 1 of this embodiment includes an electric field concentration and mitigation electrode 7. The electric field concentration and mitigation electrode 7 is electrically connected to the lid 22 so as to be at the same potential as the photocathode 3. In this embodiment, the electric field concentration and mitigation electrode 7 is an electrode that is in direct contact with the lid 22. The electric field concentration and mitigation electrode 7 is a conductive member comprising an annular plate portion 7x having an annular shape centered on the axis G and a flat plate-like shape with its thickness oriented in the direction of the axis G, and a peripheral wall portion 7g extending vertically from the outer periphery of the annular plate portion 7x. The electric field concentration and mitigation electrode 7 is airtightly connected between the insulating cylinder 14 of the housing 2 and the lid 22.

[0046] The annular plate portion 7x, which is a part of the electric field concentration mitigation electrode portion 7, is located on the electron detection portion 4 side relative to the main body portion 91 of the gate electrode portion 9 in the axis G direction (relative direction). Specifically, the annular plate portion 7x and the annular plate portion 8x of the second focusing electrode portion 8 are located at approximately the same position in the axis G direction. The electric field concentration mitigation electrode portion 7 is configured with the second focusing electrode portion 8 in its through hole 7a. Such an electric field concentration mitigation electrode portion 7 shifts the equipotential line of the potential (cathode potential) of the photoelectric element 3 toward the electron detection portion 4 side, mitigating the concentration of the electric field formed inside the shell portion 2. The electric field concentration mitigation electrode portion 7 constitutes the first electric field concentration mitigation electrode portion.

[0047] As described above, in the electron tube 1, since the power supply portion 92 of the gate electrode portion 9 is held by the cover portion 22, it is no longer necessary, for example, to arrange and hold the power supply portion 92 so as to extend parallel to the photoelectric element 3. Consequently, the volume of the components constituting the power supply portion 92 can be reduced, and the electrostatic capacitance between the photoelectric element 3 and the gate electrode portion 9 can be reduced. Consequently, the switching of the voltage applied to the gate electrode portion 9 is accelerated, and the operation of the gate electrode portion 9 can be accelerated.

[0048] The electron tube 1 includes a second focusing electrode 8 between the photocathode 3 and the electron detection section 4. The gate electrode 9 is electrically connected to the second focusing electrode 8. This ensures reliable gate operation (control of the passage of photoelectrons) and focusing control of photoelectrons. Furthermore, the gate electrode 9 and the second focusing electrode 8 are integrally formed. This allows for efficient arrangement of the gate electrode 9 and the second focusing electrode 8.

[0049] The power supply section 92 of the electron tube 1 includes a plurality of rod-shaped members 80 and a second focusing electrode section 8. In this case, by supporting the main body 91 of the gate electrode section 9 within the housing 2 so as to be suspended from the cover 22 via the plurality of rod-shaped members 80, the volume of the components constituting the power supply section 92 can be further reduced compared to a structure in which the power supply section 92 is arranged and held parallel to the photoelectric element 3, for example. This allows for efficient reduction of the electrostatic capacitance between the photoelectric element 3 and the gate electrode section 9.

[0050] In the electron tube 1, the plurality of rods 80 include a first rod 81 that penetrates the cover 22, and a second rod 82 whose other end is embedded in the cover 22. By making the second rod 82 shorter than the first rod 81, the volume of the components constituting the power supply portion 92 can be reduced, thereby efficiently reducing the electrostatic capacitance between the photocathode 3 and the gate electrode portion 9. In addition, by embedding the other end of the second rod 82 in the cover 22, it is possible to suppress potential disturbances caused by external factors from being transmitted to the gate electrode portion 9 via the second rod 82, thereby preventing the potential of the gate electrode portion 9 from unintentionally fluctuating. In addition, the first rod 81 and the second rod 82 can be used to implement a structure in which the main body 91 of the gate electrode portion 9 is supported in a suspended manner from the cover 22.

[0051] The gate electrode 9, suspended from the cover 22, is structurally prone to electric field concentration (sharp bending of equipotential lines) around the gate electrode 9, which can lead to insufficient withstand voltage. To address this issue, the electron tube 1 includes an electric field concentration mitigation electrode 7. This electrode 7 is formed to counteract the withstand voltage, namely, with the annular plate 7x positioned closer to the electron detection portion 4 than the main body 91 in the direction of the axis G. With this configuration, the electric field concentration mitigation electrode 7 mitigates electric field concentration within the housing 2, thereby improving the withstand voltage of the electron tube 1.

[0052] Figure 4 For the general Figure 1 A cross-sectional view showing a portion of the interior of the housing 2 is enlarged. Figure 4 In the figure, the group of equipotential lines inside the housing 2 is shown (described later). Figure 5 and Figure 6 Same as in ). Figure 4 As shown, the electric field concentration mitigation electrode 7 can shift the equipotential lines (cathode potential) closest to the photoelectric element 3 toward the electron detection portion 4, thereby suppressing electric field concentration (sharp bending of these potential lines). The electric field concentration mitigation electrode 7 guides these potential lines in a direction perpendicular to the axis G, thereby suppressing their intrusion (invasion) into the photoelectric element 3. The electric field concentration mitigation electrode 7 can mitigate the concentration of the electric field within the housing 2, thereby improving the withstand voltage of the electron tube 1.

[0053] [Second embodiment] Next, the second embodiment will be described. In the description of this embodiment, the points different from the first embodiment will be described.

[0054] like Figure 5As shown, the electron tube 101 of the second embodiment includes an electric field concentration alleviation electrode portion 27 instead of the electric field concentration alleviation electrode portion 7 (see Figure 1 ) differs from the first embodiment in that the electric field concentration and relaxation electrode portion 27 is electrically connected to the cover portion 22 so as to be at the same potential as the photoelectric element 3. In this embodiment, the electric field concentration and relaxation electrode portion 27 is an electrode portion that is in direct contact with the cover portion 22. The electric field concentration and relaxation electrode portion 27 has a through hole 27a provided in its center. The second focusing electrode portion 8 is disposed within this through hole 27a.

[0055] The electric field concentration mitigation electrode 27 is a conductive member comprising an annular plate portion 27x having an annular shape centered on the axis G and a flat plate-like shape with its thickness oriented in the direction of the axis G, and a peripheral wall portion 27g extending vertically from the outer periphery of the annular plate portion 27x. The electric field concentration mitigation electrode 27 is airtightly connected between the insulating tube 14 and the cover 22 of the housing 2.

[0056] The inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigating electrode portion 27 is located closer to the electron detection portion 4 than the main body portion 91 of the gate electrode portion 9 in the direction of the axis G. Specifically, the inner circumferential end 27x1 of the annular plate portion 27x is located at approximately the same position as the annular plate portion 8x of the second focusing electrode portion 8 in the direction of the axis G. The inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigating electrode portion 27 extends in a direction orthogonal to the axis G direction (a direction intersecting the axis G direction) to a position close to the power supply portion 92, particularly, in this embodiment, the annular plate portion 8x of the second focusing electrode portion 8. In other words, in the orthogonal direction (intersecting direction) perpendicular to the axis G direction, the distance H1 between the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 and the outer circumferential edge of the annular plate portion 8x opposite thereto is shorter than the distance H2 between the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 and the outer circumferential end 27x2 of the annular plate portion 27x. In this embodiment, the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 extends in the orthogonal direction (intersecting direction) perpendicular to the axis G direction until it reaches the airtight seal 22s. Specifically, the inner circumferential end 27x1 of the annular plate portion 27x extends to a point close to the outer circumferential edge of the annular plate portion 8x of the second focusing electrode portion 8. An inner peripheral end portion 27x1 of the annular plate portion 27x extends in the orthogonal direction to the inner side of the intermediate electrode portion 6. The electric field concentration alleviation electrode portion 27 constitutes a second electric field concentration alleviation electrode portion.

[0057] As described above, the gate electrode 9 can also be operated at a higher speed in the electron tube 101. Furthermore, the electric field concentration mitigation electrode 27 can shift the equipotential lines (cathode potential) closest to the photoelectric element 3 toward the electron detection element 4, thereby suppressing electric field concentration (sharp bending of these potential lines). The electric field concentration mitigation electrode 27 further guides these potential lines in a direction perpendicular to the axis G, further suppressing their intrusion (intrusion) into the photoelectric element 3. The electric field concentration mitigation electrode 27 can mitigate the concentration of the electric field within the housing 2, thereby improving the withstand voltage of the electron tube 201.

[0058] [Third embodiment] Next, the third embodiment will be described. In the description of this embodiment, the points different from the second embodiment will be described.

[0059] like Figure 6 As shown, the electron tube 201 of the third embodiment includes a second focusing electrode portion 38 in which the connection portion P with one end of the rod-shaped body 80 is located on the photocathode 3 side in the axis G direction instead of the second focusing electrode portion 8 (see FIG. Figure 1 ) is different from the second embodiment in this point.

[0060] The second focusing electrode portion 38 includes a cylindrical portion 38x having a substantially cylindrical shape centered on the axis G, and a flange portion 38y provided on the outer circumference of the cylindrical portion 38x at the end facing the photoelectric element 3. The through hole 38a corresponding to the inner bore of the cylindrical portion 38x is inclined so as to increase in diameter as the diameter increases away from the photoelectric element 3, except for the end facing the photoelectric element 3. In other words, the cylindrical portion 38x has a shape such that its width (thickness) decreases in a direction orthogonal to the axis G (a direction intersecting the axis G) as the diameter increases away from the photoelectric element 3. Furthermore, in a cross-section viewed along the axis G, the inner wall of the cylindrical portion 38x, which forms the through hole 38a, forms a tapered surface that increases in diameter as the distance from the axis G increases. Meanwhile, the outer wall of the cylindrical portion 38x forms a circular surface extending along the axis G. Furthermore, the surface (top surface) of the cylindrical portion 38x facing the photoelectric element 3 is an annular flat surface extending in a direction perpendicular to (intersecting) the axis G. Furthermore, the connecting areas between the top surface and the inner wall, and between the outer wall and the inner wall, of the cylindrical portion 38x both have rounded corners. This reduces the disturbance of the electric field caused by the corners, thus suppressing discharge.

[0061] The flange portion 38y is in the shape of a circular plate with the axis G direction as the thickness direction. The flange portion 38y is provided so as to protrude radially outward from the outer peripheral surface of the upper surface side of the cylindrical portion 38x. The upper surface of the flange portion 38y and the upper surface of the cylindrical portion 38x are flush with each other. In addition, the end portion of the flange portion 38y that protrudes radially outward has an R shape with a rounded corner. This can suppress the disorder of the electric field caused by the corner and suppress discharge. At multiple locations of the flange portion 38y, one end portion of the rod-shaped body 80 extending along the axis G direction is fixedly connected at the connection portion P, for example, by laser welding.

[0062] The inner peripheral end 27x1 of the annular plate portion 27x of the electric field concentration mitigating electrode portion 27 is located closer to the electron detection portion 4 than the connection point P between the rod-shaped body 80 and the second focusing electrode portion 38 in the direction of the axis G. Furthermore, the inner peripheral end 27x1 of the annular plate portion 27x of the electric field concentration mitigating electrode portion 27 extends in a direction orthogonal to the axis G (a direction intersecting the axis G) to a position close to the power supply portion 92, particularly, in this embodiment, the cylindrical portion 38x of the second focusing electrode portion 38. In other words, in the orthogonal direction (intersecting direction) perpendicular to the axis G direction, the distance H3 between the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 and the outer wall surface of the cylindrical portion 38x opposite thereto is shorter than the distance H4 between the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 and the outer circumferential end 27x2 of the annular plate portion 27x. In this embodiment, the inner circumferential end 27x1 of the annular plate portion 27x of the electric field concentration mitigation electrode portion 27 extends in the orthogonal direction (intersecting direction) perpendicular to the axis G direction until it reaches the airtight seal 22s, and in this case, until it reaches the flange portion 38y. The inner circumferential end 27x1 of the annular plate portion 27x extends further inward than the intermediate electrode portion 6 in the orthogonal direction. The electric field concentration mitigation electrode portion 27 constitutes the third electric field concentration mitigation electrode portion.

[0063] As described above, in the electron tube 201, the operation of the gate electrode portion 9 can also be accelerated. Furthermore, in the electron tube 201, the connection point P between the second focusing electrode portion 38 and one end of the rod-shaped body 80 can be located on the side of the photocathode 3 in the direction of the axis G, where it is less susceptible to the influence of the electric field. In the electron tube 201, the electric field concentration mitigation electrode portion 27 can mitigate the concentration of the electric field within the housing portion 2, thereby improving the withstand voltage of the electron tube 201.

[0064] Furthermore, in this embodiment, it is also possible to Figure 7As shown, the electrode portion 57, the conductive cylindrical portion 16, and the electric field concentration mitigation electrode portion 37 are provided instead of the electric field concentration mitigation electrode portion 27. The electrode portion 57 is electrically connected to the lid portion 22 and, in this embodiment, is the electrode portion that directly contacts the lid portion 22. It has a through hole 57a provided in the center portion. The electrode portion 57 is a conductive member having an annular plate portion 57x with an annular shape centered on the axis G and a flat plate with a thickness direction along the axis G, and a peripheral wall portion 57g provided upright on the outer periphery of the annular plate portion 57x. The conductive cylindrical portion 16 is a conductive member having a cylindrical shape centered on the axis G.

[0065] The electric field concentration mitigation electrode portion 37 is a conductive member having an annular shape with the axis G as its center axis and a flat plate shape with the axis G direction as its thickness direction. The electric field concentration mitigation electrode portion 37 includes an annular plate portion 37a that extends into the housing portion 2. The annular plate portion 37a is the portion of the electric field concentration mitigation electrode portion 37 that extends into the housing portion 2. An end portion 37a1 on the inner circumferential side of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 is located closer to the electron detection portion 4 than the connection point P between the rod-shaped body 80 and the second focusing electrode portion 38 in the axis G direction. The end portion 37a1 on the inner circumferential side of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 extends in an orthogonal direction (intersecting direction) perpendicular to the axis G direction to a position close to the power supply portion 92, particularly, the cylindrical portion 38x of the second focusing electrode portion 38 in this embodiment. In other words, in the orthogonal direction (intersecting direction) perpendicular to the axis G direction, the distance H5 between the inner circumferential end 37a1 of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 and the outer wall surface of the cylindrical portion 38x opposite thereto is shorter than the distance H6 between the inner circumferential end 37a1 of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 and the outer circumferential end 37a2 of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37. In this embodiment, the inner circumferential end 37a1 of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 extends in the orthogonal direction (intersecting direction) perpendicular to the axis G direction until it reaches the airtight seal 22s, and in this case, until it reaches the flange portion 38y. The inner circumferential end 37a1 of the annular plate portion 37a of the electric field concentration mitigation electrode portion 37 extends inwardly relative to the intermediate electrode portion 6 in the orthogonal direction. The electric field concentration alleviation electrode portion 37 constitutes a fourth electric field concentration alleviation electrode portion.

[0066] The electrode portion 57, the conductive cylindrical portion 16, and the electric field concentration mitigation electrode portion 37 are stacked in sequence and electrically connected to each other. The electrode portion 57, the conductive cylindrical portion 16, and the electric field concentration mitigation electrode portion 37 are airtightly connected between the cover portion 22 and the insulating cylindrical portion 14 of the housing 2. With this configuration, the electric field concentration mitigation electrode portion 37 can mitigate the concentration of the electric field within the housing 2, thereby improving the withstand voltage of the electron tube 201.

[0067] As mentioned above, although embodiment was described, one aspect of this disclosure is not limited to the above-mentioned embodiment.

[0068] In the above embodiment, the gate electrode unit 9 is integrally provided with the second focusing electrode unit 8. However, the gate electrode unit 9 may also be provided separately from the second focusing electrode unit 8. In this case, the gate electrode unit 9 may be electrically connected to the second focusing electrode unit 8 via a conductive member, or may include a separate power supply unit. The above embodiment includes the first rod-shaped body 81 and the second rod-shaped body 82, but it may also include only the first rod-shaped body 81.

[0069] In the above embodiment, the main body 91 of the gate electrode 9 is electrically connected to the rod 80 via the second focusing electrode 8 . However, instead of or in addition to this, the main body 91 may be electrically connected to the rod 80 via another conductive member.

[0070] In the above embodiment, the photoelectric surface 3 is a curved surface. However, the shape of the photoelectric surface 3 is not limited to a curved surface and can be various shapes. For example, the photoelectric surface 3 can be a flat surface. In the above embodiment, the photoelectric surface 3 is a reflective photoelectric conversion unit, but it can also be a transmissive photoelectric conversion unit.

[0071] In the above embodiment, an avalanche photodiode is used as the electron detection unit 4, but the present invention is not limited thereto. The electron detection unit may use other semiconductor electron detection elements and may include only an anode or a dynode and an anode.

[0072] The various components of the above-mentioned embodiment and the above-mentioned variations are not limited to the above-mentioned materials and shapes, and various materials and shapes can be applied. The various components of the above-mentioned embodiment or variations can be arbitrarily applied to the various components of other embodiments or variations. Parts of the various components of the above-mentioned embodiment or variations can be appropriately omitted within the scope of the gist of one aspect of the present disclosure. Explanation of symbols

[0073] 1, 101, 201…electron tube, 2…casing portion, 3…photoelectric surface (photoelectric conversion portion), 4…electron detection portion, 7…electric field concentration and relaxation electrode portion (first electric field concentration and relaxation electrode portion), 8…second focusing electrode portion (focusing electrode portion, connecting portion), 9…gate electrode portion, 22…cover portion, 22h, 22s…airtight seal (airtight seal portion), 27…electric field concentration and relaxation electrode portion (second electric field concentration and relaxation electrode portion, third electric field concentration and relaxation electrode portion), 37…electric field concentration and relaxation electrode portion (fourth electric field concentration and relaxation electrode portion), 80…rod-shaped body, 81…first rod-shaped body, 82…second rod-shaped body, 91…main body, 92…power supply portion, P…connecting portion.

Claims

1. An electron tube, comprising: a photoelectric conversion unit that emits photoelectrons in response to incident light; an electron detection unit that receives photoelectrons from the photoelectric conversion unit; a gate electrode portion disposed between the photoelectric conversion portion and the electron detection portion; and a housing portion that houses the photoelectric conversion portion, the electron detection portion, and the gate electrode portion; The housing part, A cover portion is provided to which the photoelectric conversion portion is fixed and constitutes one end side of the housing portion. The gate electrode portion includes: a main body portion that controls the passage of photoelectrons by applying a voltage; and a power supply unit that supports the main body unit in a manner separated from the photoelectric conversion unit and applies a voltage to the main body unit, The power supply portion is held by the cover portion.

2. The electron tube according to claim 1, wherein The focusing electrode portion is provided between the photoelectric conversion portion and the electron detection portion and faces the photoelectric conversion portion to focus the photoelectrons from the photoelectric conversion portion. The gate electrode portion is electrically connected to the focusing electrode portion.

3. The electron tube according to claim 2, wherein: The gate electrode portion and the focusing electrode portion are integrated.

4. The electron tube according to claim 1, wherein The power supply unit includes: a plurality of rod-shaped bodies, which are fixed to the cover portion and have one end portion located in the housing portion; and A connecting portion connects one end portion of the plurality of rod-shaped bodies to the main body portion.

5. The electron tube according to claim 4, wherein The plurality of rod-shaped bodies include: a first rod-shaped body penetrating the cover; and The other end portion of the second rod-shaped body is embedded in the cover portion.

6. The electron tube according to claim 1, wherein The first electric field concentration mitigating electrode portion is electrically connected to the cover portion so as to have the same potential as the photoelectric conversion portion and mitigates the concentration of the electric field formed inside the housing portion. A portion of the first electric field concentration alleviation electrode portion is located closer to the electron detection portion than the main body portion in the opposing direction of the photoelectric conversion portion and the electron detection portion.

7. The electron tube according to claim 4, wherein The second electric field concentration mitigating electrode portion is electrically connected to the cover portion so as to have the same potential as the photoelectric conversion portion and mitigates the concentration of the electric field formed inside the housing portion. The end portion on the inner side of the shell portion in the second electric field concentration mitigation electrode portion is located closer to the electron detection portion than the main body portion in the relative direction between the photoelectric conversion portion and the electron detection portion, and extends to a position close to the power supply portion in the intersecting direction intersecting the relative direction.

8. The electron tube according to claim 7, wherein The rod-shaped body is fixed to the cover portion via an airtight seal portion, An end portion of the second electric field concentration alleviation electrode portion on the inner side of the casing portion extends in the intersecting direction until it reaches the hermetic seal portion.

9. The electron tube according to claim 4, wherein The third electric field concentration mitigating electrode portion is in contact with the cover portion so as to have the same potential as the photoelectric conversion portion and mitigates the concentration of the electric field formed inside the housing portion. An end portion of the third electric field concentration mitigating electrode portion on the inner side of the shell portion is located closer to the electron detection portion than a connection portion between the rod-shaped body and the connection portion in the relative direction of the photoelectric conversion portion and the electron detection portion.

10. The electron tube according to claim 9, wherein One end portion of the third electric field concentration alleviation electrode portion extends in a direction intersecting the opposing direction until it reaches the connection portion.

11. The electron tube according to claim 4, wherein The fourth electric field concentration mitigation electrode portion extends in a direction intersecting the relative direction of the photoelectric conversion portion and the electron detection portion, has one end portion located inside the housing portion and the other end portion located outside the housing portion, and mitigates the concentration of the electric field formed inside the housing portion. One end portion of the fourth electric field concentration mitigating electrode portion is located closer to the electron detecting portion than a connection point between the rod-shaped body and the connecting portion in the opposing direction, and extends to a position close to the power supply portion in the intersecting direction.

12. The electron tube according to claim 11, wherein One end portion of the fourth electric field concentration alleviation electrode portion extends in the intersecting direction until it reaches the connection portion.

Images